THanks. The Rayquals he carries are said to be the best, made in Japan by a skilled machine shop specializing in camera mounts. I was pleasantly surprised by the Fotodiox Pro, though. One thing that I stumble over is the clockwise vs counterclockwise mounting of Canon and Nikon - habit is to do it the Canon way, before ...oh yeah... the Nikon way. I have had decent luck with the cheap eBay M42 to EOS adapters, but those are mechanically very simple. Some of the old lenses have pleasing rendering, though the modern lenses beat them in resolution, by and large. The old fast normal lenses have spectacular coma in full frame corners, only controllable at f/4. Interestingly, I have two essentially identical 55mm f/1.4 lenses of similar vintage and apparently identical element design, Mamiya Sekor and Chinon, and the Chinon is significantly better for coma - probably the coatings are different, or batch of glass was different, even though it is often claimed that both are Tomioka made.